Stink bugs can twist corn

Stink bug damage to corn occurs widely across Iowa but is mostly seen in fields with winter annual weeds or in corn plants adjacent to weedy fence rows. Basic symptoms of stink bug injury are stunted plants that may grow lateral shoots; wrinkled leaves; holes of various sizes, scattered randomly or in repeating patterns often with a yellow halo; and whorl leaves wrapped tight and failing to expand. Injury is most common on newly emerged plants through the 4th true-leaf stage, but it also may occur on mid-whorl-stage plants. Stink bugs pierce the side of the stalk with their beak. Saliva injected into the leaf during feeding creates holes from pinhole diameter up to 1 inch on expanded leaves. Holes are often surrounded by dead, brown tissue and a yellow halo. Feeding patterns are often repeated across the leaf, possibly giving the appearance of severe shot hole injury from European corn borer larvae. Injured leaves are often twisted giving the plant a “buggy whip” appearance and terminal leaves may fail to fully develop because of the twisting. Heavily injured plants that are not killed by the feeding grow new lateral shoots (tillers). Insecticide control is rarely warranted because most injury is diagnosed after the problem has occurred.